AdventOfCode/2017/03/3.md

## \-\-- Day 3: Spiral Memory \-\--

You come across an experimental new kind of memory stored on an
[infinite two-dimensional
grid]{title="Good thing we have all these infinite two-dimensional grids lying around!"}.

Each square on the grid is allocated in a spiral pattern starting at a
location marked `1` and then counting up while spiraling outward. For
example, the first few squares are allocated like this:

    17  16  15  14  13
    18   5   4   3  12
    19   6   1   2  11
    20   7   8   9  10
    21  22  23---> ...

While this is very space-efficient (no squares are skipped), requested
data must be carried back to square `1` (the location of the only access
port for this memory system) by programs that can only move up, down,
left, or right. They always take the shortest path: the [Manhattan
Distance](https://en.wikipedia.org/wiki/Taxicab_geometry) between the
location of the data and square `1`.

For example:

-   Data from square `1` is carried `0` steps, since it\'s at the access
    port.
-   Data from square `12` is carried `3` steps, such as: down, left,
    left.
-   Data from square `23` is carried only `2` steps: up twice.
-   Data from square `1024` must be carried `31` steps.

*How many steps* are required to carry the data from the square
identified in your puzzle input all the way to the access port?

Your puzzle answer was `371`.

## \-\-- Part Two \-\-- {#part2}

As a stress test on the system, the programs here clear the grid and
then store the value `1` in square `1`. Then, in the same allocation
order as shown above, they store the sum of the values in all adjacent
squares, including diagonals.

So, the first few squares\' values are chosen as follows:

-   Square `1` starts with the value `1`.
-   Square `2` has only one adjacent filled square (with value `1`), so
    it also stores `1`.
-   Square `3` has both of the above squares as neighbors and stores the
    sum of their values, `2`.
-   Square `4` has all three of the aforementioned squares as neighbors
    and stores the sum of their values, `4`.
-   Square `5` only has the first and fourth squares as neighbors, so it
    gets the value `5`.

Once a square is written, its value does not change. Therefore, the
first few squares would receive the following values:

    147  142  133  122   59
    304    5    4    2   57
    330   10    1    1   54
    351   11   23   25   26
    362  747  806--->   ...

What is the *first value written* that is *larger* than your puzzle
input?

Your puzzle answer was `369601`.

Both parts of this puzzle are complete! They provide two gold stars:
\*\*

At this point, you should [return to your Advent calendar](/2017) and
try another puzzle.

Your puzzle input was `368078`{.puzzle-input}.